1. Field of the Invention
The invention relates to an engine system that has a turbocharger which is provided with a variable nozzle mechanism and a fuel addition device which performs fuel addition to exhaust gas and a control apparatus and a control method for an engine system.
2. Description of Related Art
Japanese Patent Application Publication No. 2006-152948 (JP 2006-152948 A) discloses a turbocharger that is provided with a variable nozzle mechanism. The variable nozzle mechanism is provided with a plurality of nozzle vanes around a turbine wheel in a flow path (exhaust flow path) through which exhaust gas passes in an exhaust turbine. The plurality of nozzle vanes are arranged at predetermined intervals around the axis of rotation of the turbine wheel. The nozzle vanes are connected to each other by a link mechanism in a link chamber adjacent to the exhaust flow path and are subjected to opening and closing operations in a state of being synchronized with each other. In the turbocharger, the nozzle vanes are driven to be opened and closed at the same time through operation control for the variable nozzle mechanism so that the gaps between the adjacent nozzle vanes are changed. In this manner, the flow speed of the exhaust gas that is sprayed to the turbine wheel through the spaces between the nozzle vanes is changed, and the pressure-feeding amount of intake air is adjusted.
JP 2006-152948 A discloses a fuel addition device that regularly executes fuel addition to the exhaust gas for functional recovery of an exhaust gas control apparatus (exhaust gas purifying catalyst, filter, or the like) that is disposed in an exhaust passage of an internal combustion engine. A fuel addition valve that adds a fuel to a further exhaust upstream side than a turbine in the exhaust passage is disposed in a fuel ignition device described above. The fuel is added to the exhaust gas through the fuel injection from the fuel addition valve.